Penetration Test on Bitumen
IS 1203
A standard needle loaded to 100 g is allowed to penetrate a sample of bitumen for 5 seconds at 25°C. The depth of penetration, measured in tenths of a millimetre, is the penetration value — this is literally where paving grades like "60/70" and "80/100" bitumen get their names.
Penetration value is the primary consistency grading test for paving-grade bitumen and is used to confirm a delivered batch matches its specified grade.